An intra-prediction technology stipulated in a video coding standard uses a correlation between neighboring blocks and employs multi-direction prediction to improve prediction precision. For example, in H.264, there are nine prediction directions for predicting a luminance component. An intra-prediction technology stipulated in a High Efficiency Video Coding (HEVC) standard draft is similar to an intra-prediction technology used in H.264, but the HEVC further extends a block partitioning type and the number of prediction directions, and a maximum of 33 directions are allowed for prediction. A distribution of prediction directions is illustrated in a figure below. A thick box indicates a current block, each black line indicates a prediction direction, and as shown in the figure, a prediction of a pixel in a bottom-most corner of the current block by using an upper and a left reference pixel may be performed along 33 directions. The directions may be classified into two types: (1) a direction from upper left to lower right, which is defined as a negative angle prediction direction; (2) a direction from upper right to lower left, or a direction from lower left to upper right, which is defined as a positive angle prediction direction. During a prediction process, a prediction mode is selected, and a reference pixel is then acquired according to a prediction direction indicated by the prediction mode, for example, if the prediction direction of the prediction mode points to 90 degrees relative to a current pixel, a pointed-to pixel at a border between an upper neighboring block and the current block is used as a reference pixel of the current pixel according to the prediction direction, and prediction is then performed according to a pixel value of the reference pixel. This, however, is a unidirectional prediction technology, and uses a reference pixel on only one side of a prediction direction to perform prediction, which is difficult to ensure prediction precision.